It is known to use an instrument bar to support instruments of a wind turbine. The bar is located on top of the nacelle and usually comprises wind wanes, anemometers, aviation light etc.
The instruments need to be maintained, serviced, changed or repaired during the life time of the wind turbine. Thus personal has to leave the nacelle for this purpose. This task is dangerous due to the height of the wind turbine. Sometimes it is even not possible to leave the nacelle due to the weather conditions and due to high wind speeds, etc.
The instrument bar needs to be placed on top of the nacelle at a planned site with a crane. Thus personal has to climb out of the nacelle to direct the crane and to fix the instrument bar at the nacelle. This task is dangerous, too.
FIG. 4 shows a picture of this kind of work, as it is done today. A bar B, which supports instruments INS is placed on top of a nacelle N.